Recently, substantial attention has been directed toward the development and implementation of internal and external ultrasound imaging systems.
Intraluminal, intracavity, intravascular, and intracardiac treatment and diagnosis of medical conditions utilizing minimally invasive procedures is an effective tool in many areas of medical practice. These procedures typically are performed using imaging and treatment catheters that are inserted percutaneously into the body and into an accessible vessel, such as the femoral artery, of the vascular system at a site remote from a region of the body to be diagnosed and/or treated. The catheter then is advanced through the vessels of the vascular system to the region of the body to be diagnosed and/or treated, such as a vessel or an organ. The catheter may be equipped with an imaging device, typically an ultrasound imaging device, which is used to locate and diagnose a diseased portion of the body, such as a stenosed region of an artery.
Intravascular imaging systems having ultrasound imaging capabilities generally are known. For example, U.S. Pat. No. 4,951,677, issued to Crowley, the disclosure of which is incorporated herein by reference, describes such an intravascular ultrasound imaging system. An ultrasound imaging system typically contains some type of control system, a drive shaft, and a transducer assembly including an ultrasound transducer. The transducer assembly includes a transducer element and is coupled to the control system by the drive shaft. The drive shaft typically includes an electrical cable, such as coaxial cable, for providing electrical communication between the control system and the ultrasound transducer.
In operation, the drive shaft and the transducer assembly are inserted, usually within a catheter, into a patient's body and may be positioned near a remote region of interest. To provide diagnostic scans of the remote region of interest within, for example, a coronary blood vessel, the ultrasound transducer may be positioned near or within the remote region of the patient's body. Diagnostic scans are created when the control system alternately excites and allows sensing by the ultrasound transducer. The control system may direct the ultrasound transducer toward or away from an area of the remote region. When the ultrasound transducer is excited, a transmitting/receiving surface of the transducer element creates pressure waves in the bodily fluids surrounding the ultrasound transducer. The pressure waves then propagate through the fluids within the patent's body and ultimately reach the region of interest, forming reflected pressure waves. The reflected pressure waves then return through the fluids within the patient's body to the transmitting/receiving surface of the transducer element, inducing electrical signals within the transducer element. The control system then may collect the induced electrical signals and may reposition the ultrasound transducer to an adjacent area within the remote region of the patient's body, again exciting and sensing the transducer element. This process may continue until the remote region has been examined sufficiently and a series of induced signals has been collected. The control system then may process the series of induced signals to derive a diagnostic scan and may display a complete image of the diagnostic scan.
Those skilled in the art will appreciate that the type of transducer that may be required, or preferred, for a particular procedure often will vary depending upon the type of procedure to be performed. For example, for some procedures it may be desirable to utilize a transducer with a long, or extended focus, such that areas of tissue remote from the transducer may be imaged clearly, whereas in other procedures it may be desirable to utilize a transducer with a relatively short focus to image, for example, areas of tissue in relatively close proximity to the transducer. Those skilled in the art also will appreciate that, depending upon the type of procedure to be performed, it may be desirable to utilize transducers having the ability to implement certain scanning functions. Finally, those skilled in the art will appreciate that in many imaging systems, such as those described above, a transducer will be rotated to perform a scanning function, and that the provision of such capabilities may add significantly to the cost of an imaging system.
In view of the foregoing, it is believed that a need exists for an improved ultrasound transducer that overcomes the aforementioned obstacles and deficiencies of currently available ultrasound transducers. It is further believed that a need exists for a transducer that is dynamically configurable, such that its performance may be dynamically altered to meet the needs of a given application.